Spring 2008

For more details, and talks in past semesters, consult the full schedule of talks.

Tentative talks:

Interested in speaking?

Past topics can (and should) be repeated occasionally. In addition, here are some topics people might like to hear about:

To give a talk, please contact swig@math.arizona.edu.

Home Computing: Processors

by Bob Condon

Table of Contents


OVERVIEW
When selecting a computer, it helps to have a clear understanding of its expected use. You might ask yourself:  What are the principle uses of the new machine? Consider (and prioritize) needs such as graphics, numerics, word processing, internet communications, etc..

Looking over current prices, you can (roughly) distinguish computer systems by $1000 increments. You can buy a $1000+ home system that is well-suited for internet use, book keeping, and word processing. For $2000+, you can get a much faster system . . . that might be used for work requiring considerable computation and/or graphics. For $3000+, you can buy a super-system with 3D graphics, 30 fps animation, megamemory, and excellent computational performance.

Having an idea of the base price, you might then add memory, disk, video, and/or backup peripherals (to suit your individual needs). Think for yourself . . . one person might value a bigger monitor over extra speed (do you spend more time reading/writing text on the screen or waiting for computational results). If you are writing a 21st century sequel to the Principia Mathematica, data-backup hardware might be important. Configuration is personal . . . depending on projected use.

Once you have settled on a rough budget, the rest is easy. Decode a few thousand acronyms . . . consult an astrologer . . . and buy.


ACRONYMS: WHERE to START

To understand the difference between the $1000+ and the $3000+ system, start with the central processing unit (CPU). In what follows, we will look at CPUs (specifically, those made by Intel) . . . distinguish them from one another . . . and outline what technology advances are expected in the near future.

The CPU is the major (though alterable) item that determines the base cost of your computer. Other basic system components (such as motherboard, memory, and i/o peripherals) are configured to support the choice of CPU, i.e., as you increase the expenditure on the CPU, you also will be (or should be) spending more on the motherboard, memory, disk, and (possibly) video.

The following information about Intel CPUs comes from many sources . . . all on the Internet.

  • ShoppingPlanet
    . . . used for PC Newsletter and component pricing
  • Computer Retail Week
    . . . used for info on Intel's future plans, product reports, and component pricing
  • SPEC performance ratings
  • Tom's Hardware
    . . . used for info on overclocking, system performance, the PCI bus, SDRAM, etc.
  • IBM technical info
    . . . used for specs on fpm dram, edo dram, bedo dram, and sdram memories
  • Intel
    . . . info about Pentium-xxx specs and benchmarks
  • Intel
    . . . definitive summary of all Intel processors
  • ASUS
    . . . well-reviewed motherboard manufacturer
  • Sun
    . . . info about Sun Ultra-xx specs and benchmarks


PENTIUM PRO

The Pentium Pro (often identified by the acronym P6) is a 32-bit processor (means that we don't use it for older DOS, Windows-3.x, or Windows-95, 8/16-bit, segmented memory model, software applications)!!!

The Pentium Pro processors have been built to run at various speeds (see the overclocking web page reference) . . . 150 MHz, 166 MHz, 180 MHz, and 200 MHz. To get a reference point, a Pentium processor instruction (such as ADD, STORE, XOR) will take a number (say 15) of clock cycles .. meaning that you might be able to add two numbers 13.33 million times in one second (with a 200 MHz Pentium Pro CPU).

The Pentium processors run at speeds that greatly exceed the capabilities of other system components . . . such as the memory (25 MHz to 66 MHz) and the bus (66 MHz). To help keep the processor running at top speed, Intel adds some extra-fast "level-1 cache" memory (for a price) to the internal of the CPU chip .. and provides more (sometimes slightly slower) "level-2 cache" memory in a "tightly coupled" configuration.

All Pentium Pro CPUs have 16K of L1 cache (8K instruction + 8K data).

A Pentium Pro system can be bought with 256K, 512K, and 1Mb (for P-Pro 200 MHz) of L2 cache. Pentium Pro L2 cache -- which is integrated onto a single CPU, cache, bus interface chip/package -- runs at CORE SPEED!!!

The variations in processor speed and cache configurations define the potential processor performance (as measured by the Standard Performance Evaluation Corporation <SPEC> composite integer and floating point benchmarks). These variations are subsequently reflected in (sample) Pentium Pro prices:

  • 200 MHz (with 1Mb cache) $2675 (Intel wholesale, Aug/1997)
  • 200 MHz (with 512K cache) $1345 (WJM, Jan/1998)
  • 200 MHz (with 256K cache) $581 (WJM, Jan/1998)

Why would the price vary?

  • Pentium Pro CPU has ~5.5 million transistors.
  • Pentium Pro 1Mb cache has ~62 million transistors.
  • Pentium Pro 512K cache has ~31.0 million transistors.
  • Pentium Pro 256K cache has ~15.5 million transistors.

For nerds:

  • Pentium Pro uses .35-micron CMOS process technology.
  • Pentium Pro has 64 bit data/address bus interface.
  • Pentium Pro has 64 bit L2 cache bus interface.
  • Pentium Pro uses the standard "socket 8" .. requires its own standard motherboard. Pentium Pro socket can be adapted for "Single Edge Contact" cards being used for Pentium II CPUs (see below).

Why has the Pentium Pro been a good choice for processor intensive (computational) applications?

  • Pentium Pro supports "dynamic execution" and is "superscalar" in design.
  • Dynamic Execution provides (look ahead) "multiple branch prediction" (guesses based on a Branch Target Buffer cache of program code branch history), "dataflow analysis" (the re-ordering of instruction execution -- when possible -- to avoid slowdowns due to data/instruction dependencies), and "speculative execution" (advance processing based on the correct branch assumption and proper re-ordereding of all dependencies). Dynamic execution is stored in a "temporary architectural state" .. and is committed to permanent status based on actual program flow.
  • Superscalar design enables simultaneous fetching, decoding, and executing of multiple integer operations per single clock cycle (instructions being fed into separate execution unit pipelines).

For more detailed info, look over the P6 "dynamic execution" glossary at INTEL.

So how fast is a Pentium Pro? . . . using the SPEC composite benchmarks.

  • Pentium Pro 200 MHz SPECint95 == 8.66 (with 1 Mb L2)
  • Pentium Pro 200 MHz SPECfp95 == 6.80 (with 1 Mb L2)
  • Pentium Pro 200 MHz SPECint95 == 8.58 (with 512K L2)
  • Pentium Pro 200 MHz SPECfp95 == 6.48 (with 512K L2)
  • Pentium Pro 200 MHz SPECint95 == 8.09 (with 256K L2)
  • Pentium Pro 200 MHz SPECfp95 == 6.75 (with 256K L2)
  • Pentium Pro 180 MHz SPECint95 == 7.29 (with 256K L2)
  • Pentium Pro 180 MHz SPECfp95 == 6.08 (with 256K L2)
  • Pentium Pro 150 MHz SPECint95 == 6.08 (with 256K L2)
  • Pentium Pro 150 MHz SPECfp95 == 5.42 (with 256K L2)
  • Sun Sparc20 model 151 SPECint95 == 4.02
  • Sun Sparc20 model 151 SPECfp95 == 4.71
  • Sun UltraII 2200 (2 CPU) SPECint95 == 7.81
  • Sun UltraII 2200 (2 CPU) SPECfp95 == 14.7
  • SGI Power Challenge R10000 (195 MHz -- 2 CPU) SPECint95 == 8.85
  • SGI Power Challenge R10000 (195 MHz -- 2 CPU) SPECfp95 == 12.4
  • SGI Origin 200 (1 CPU) SPECint95 == 10.3
  • SGI Origin 2000 (2 CPU) SPECint95 == 11.3
  • SGI Origin 2000 (2 CPU) SPECfp95 == 19.1
  • SGI O2 R5000SC SPECint95 == 4.82
  • SGI O2 R5000SC SPECfp95 == 5.42


PENTIUM with MMX

What is MMX?

Pentium MMX is 57 new CPU instructions .. implementing a SIMD (single instuction on multiple data) capability that should be useful in graphics and signal processing applications. Intent is to accelerate graphics, multi-media, and communications tasks. Pentium MMX is not intended to replace 2D and 3D graphics cards, (Intel example: machine with 3D card doing 30 frames/second would now do 70 fps).

Pentium MMX comes with clock speeds of 166 MHz, 200 MHz, and 233 MHz (for desktops) .. 150 MHz and 166 MHz (for laptops).

What does the Pentium with MMX processor cost?

  • 200 MHz $160 (WJM, Jan/1998)
  • 166 MHz $130 (WJM, Jan/1998)

What will the Pentium with MMX processor cost?

  • 200 MHz $92 (Intel wholesale, Apr/1998)
  • 166 MHz $92 (Intel wholesale, Apr/1998)
  • 166 MHz -- (gone in Jul/1998)

For nerds:

  • Pentium without MMX (P54C) .. has ~3.3 million transistors.
  • Pentium with MMX (P55C) .. has ~4.5 million transistors.
  • Pentium MMX uses .35-micron CMOS process technology.
  • Pentium with MMX has 64 bit data bus interface.
  • Pentium with MMX has 32 bit address bus interface.
  • Pentium MMX uses the P54C standard "socket 7" .. same motherboard as P54C (with reservations). Pentium MMX on P54C motherboard requires "dual voltage" capability .. or "single adjustable voltage" (resulting in lower performance). Intel sells a "Tucson" board especially designed for MMX processors.

Other than added instructions, what distinguishes the Pentium with MMX processor?

  • Pentium MMX has 32K L1 cache (P54C had 16K cache).
  • Pentium MMX has "improved instruction pipeline" (better branch prediction) .. to reduce wait states .. with expected performance gain of 5% to 15%.
  • Pentium MMX (without use of MMX instructions) should improve performance by 10% to 20%.
  • Pentium MMX (with use of MMX instructions) should improve performance by 25% to 400%).

So how fast is a Pentium with MMX? . . . using the SPEC composite benchmarks.

  • Pentium MMX 233 MHz SPECint95 == 7.12
  • Pentium MMX 233 MHz SPECfp95 == 5.21
  • Pentium MMX 200 MHz SPECint95 == 6.44
  • Pentium MMX 200 MHz SPECfp95 == 4.87
  • Pentium MMX 166 MHz SPECint95 == 5.60
  • Pentium MMX 166 MHz SPECfp95 == 4.34

Are these numbers an improvement?

  • Pentium 200 MHz SPECint95 == 5.17
  • Pentium 200 MHz SPECfp95 == 4.32
  • Pentium Pro 200 MHz SPECint95 == 8.09 (with 256K L2)
  • Pentium Pro 200 MHz SPECfp95 == 6.75 (with 256K L2)

What happened to the Pentium with MMX versus the Pentium Pro?
. . . might be the lack of an L2 cache.


PENTIUM II

The Pentium II is (almost) a Pentium Pro with MMX. The Intel codename for the desktop Pentium II (233/266/300) CPU is "Klamath". The Intel codename for the notebook CPU is "Tillamook".

What does the Pentium II cost?

  • 300 MHz $595 (WJM, Jan/1998)
  • 266 MHz $427 (WJM, Jan/1998)
  • 233 MHz $333 (WJM, Jan/1998)

What will the Pentium II cost?

  • 300 MHz $370 (Intel wholesale, Apr/1998)
  • 300 MHz $300 (Intel wholesale, Jun/1998)
  • 300 MHz $200 (Intel wholesale, Aug/1998)
  • 266 MHz $195 (Intel wholesale, Apr/1998)
  • 266 MHz $155 (Intel wholesale, Aug/1998)
  • 233 MHz $195 (Intel wholesale, Apr/1998)
  • 233 MHz $105 (Intel wholesale, Aug/1998)

For nerds:

  • Pentium II has ~7.5 million transistors.
  • Pentium II (233, 266, 300) utilizes .35-micron process technology.
  • Pentium II has 64 bit system bus interface.
  • Pentium II has 64 bit L2 cache bus interface.

What distinguishes the Pentium II design?

  • Pentium II CPU does not utilize the (formerly) standard "Pin Grid Array" .. but uses the (standard) "Single Edge Contact" (SEC).
  • Pentium II CPU has 32Kb of L1 cache (P-Pro had 16 Kb).
  • Pentium II "SEC" has 512Kb of closely-coupled L2 cache (which is implemented using off-CPU SRAM .. running at 50% of CPU clock speed .. rather than the fixed 66 MHz of the P54C systems .. or the CORE SPEED of P-Pro systems).
  • Pentium II SEC will use the P-Pro "dual independent bus" (for CPU to main memory and CPU to L2 cache transfers) .. resulting in (up to) 3 times performance increase over the P54C "socket 7" design.

Some practical info:

  • Pentium II will have a CPU fan .. and the SEC card will have a 2nd system fan pointed at it (cooling for future higher speeds).
  • Pentium II has MMX instructions built-in, but "normal" applications may hardly benefit from MMX (reviews as of June, 1997).

So how fast is the Pentium II?

  • Pentium II 300 MHz SPECint95 == 11.7
  • Pentium II 300 MHz SPECfp95 == 8.15
  • Pentium II 266 MHz SPECint95 == 10.8
  • Pentium II 266 MHz SPECfp95 == 7.68
  • Pentium II 233 MHz SPECint95 == 9.47
  • Pentium II 233 MHz SPECfp95 == 7.04
  • Pentium Pro 200 MHz SPECint95 == 8.58 (with 512K L2)
  • Pentium Pro 200 MHz SPECfp95 == 6.48 (with 512K L2)


PENTIUM II/333   (Feb, 1998)

The Intel codename for the Pentium II/333 CPU is "Deschutes". The .25-micron (1/400th of a human hair) manufacturing process will allow higher CPU clock speeds using lower electrical voltages with less generated heat.

What will the Pentium II/333 cost?

  • 333 MHz $710 (Intel wholesale, Jan/1998)
  • 333 MHz $815 (WJM, Jan/1998) +14.8%
  • 333 MHz $570 (Intel wholesale, Mar/1998)
  • 333 MHz $480 (Intel wholesale, Apr/1998)
  • 333 MHz $400 (Intel wholesale, Jun/1998)

For nerds:

  • Pentium II/333 "SEC" will be unchanged .. having 512Kb of closely-coupled (off-CPU, 50% processor speed) L2 cache.
  • Pentium II/333 SEC will have the P-Pro "dual independent bus" (for CPU to main memory and CPU to L2 cache transfers).
  • Pentium II/333 has ~7.5 million transistors.
  • Pentium II/333 utilizes .25-micron process technology (allowing future speed-ups and lower costs).
  • Pentium II/333 has 64 bit system bus interface.
  • Pentium II/333 has 64 bit L2 cache bus interface.
  • Pentium II/333 has MMX instructions.

So how fast is the Pentium II?

  • Pentium II/333 SPECint95 == 12.8
  • Pentium II/333 SPECfp95 == 9.14
  • Pentium II 300 MHz SPECint95 == 11.7
  • Pentium II 300 MHz SPECfp95 == 8.15
  • Pentium Pro 200 MHz SPECint95 == 8.58 (with 512K L2)
  • Pentium Pro 200 MHz SPECfp95 == 6.48 (with 512K L2)


NEAR FUTURE PENTIUM IIs   (1998)

What's in store for future Pentium II/xxx processors?

  • Future Deschutes CPUs will support a 100 MHz CPU bus interface. &nsbp (see overclocking web page)
  • Future Deschutes CPUs will support 1 Mb of L2 cache.
  • Slot II Processor Card (June, 1998) ... will feature a (version II) 400 MHz CPU with 512K/1MB/2MB of L2 cache that runs at CORE SPEED!!! &nsbp (like Pentium Pro)

Laptop Fans:there will be LapTop Pentium II in March.

Astrology:

  • the "Covington" ... no-cache, $150 (Apr/1998), for sub $1,000 systems
  • the "Mendocino" ... (smaller) on-chip L2 cache, will run at 300/333 MHz (Jul/1998)
  • the "Katami" ... enhanced MMX instructions, larger (1 Mb) cache, higher (400+ MHz) clock speeds
  • the "Willamette" ... additional execution hardware, 100 MHz bus, higher (400+ MHz) clock speeds. Expected performance is to be ~1.5 that of the Pentium II (which ine) .. which would be minimum SPECint~=20.0 and SPECfp~=15.0
  • the "Merced" .. a 64-bit architecture being developed in conjunction with HP (for 1999+)

What will the new Pentium II/xxx processors cost?

  • 350 MHz Pentium II $610 (Apr/1998) ... using 100 MHz system bus
  • 350 MHz Pentium II $510 (Jun/1998) ... using 100 MHz system bus
  • 350 MHz Pentium II $415 (Aug/1998) ... using 100 MHz system bus
  • 400 MHz Pentium II $810 (Apr/1998) ... using 100 MHz system bus
  • 400 MHz Pentium II $710 (Jun/1998) ... using 100 MHz system bus
  • 400 MHz Pentium II $580 (Aug/1998) ... using 100 MHz system bus
  • 400 MHz Pentium II+ $760 (~Aug/1998) ... 100 MHz system bus, new cache
  • 450 MHz Pentium II+ $760 (~Aug/1998) ... 100 MHz system bus, new cache


MOTHERBOARDS

If you've decided to purchase an advanced CPU, make sure to get a motherboard to match. If you are going to build a dual-boot system, want to use the newest hardware, and/or want high performance, know that all motherboards are not the same.

  • we've successfully used ASUS, TYAN, and Intel
  • we've seen good reviews on M-Technology
  • we've had lots of problems (no phone numbers, manuals, or specs) trying to get SCSI, ethernet, and sound cards working with "no-name" brands

To see an example "extra good" board, check out the "ASUS P2L97" (at $209) for Pentium IIs. On the net (see "ShoppingPlanet" web pages), we see that the ASUS P2L97 has:

  • the Intel LX AGP (accelerated graphics port) Chipset,
  • 2 ISA slots
  • 5 PCI slots
  • 1 AGP slot
  • ATX form factor
  • Pentium II Single Edge Contact slot (512K or 256K L2 cache)
  • three 168-pin DIMM memory sockets that supporting 8, 16, 32, 64, or 128 MB EDO DRAM or SDRAM (see nelow, MEMORY)
  • 1 floppy port
  • 2 high speed (16550) serial ports
  • 1 parallel port
  • two ultra-dma IDE ports (4 disk drives) with ATAPI cd-rom support
  • ATX power connector with built-in adjustable voltage regulator
  • Award AGP bios
  • PS/2 mouse port
  • PS/2 keyboard port
  • 2 USB (universal serial bus) ports


MEMORY

A major system design objective is to avoid (as much as possible) performance bottlenecks. The CPU (running at speeds commonly exceeding 300 MHz) is connected to a system bus (that is commonly clocked at 66 MHz) .. onto which is connected the memory subsystem (which must be accessed at various <often even slower> speeds).

To fetch/store data at the 66 MHz system bus speed, the CPU needs to access memory within 15 ns. Timings for true random access (running over all of memory) get skewed by a set-up time .. penalty for accessing bit #1 on a page. To compensate, manufacturers usually quote speeds assuming a ~sequential access .. using a 4 bit burst read/write (to the same page). For example, the "speed" of 60 ns FPM DRAM .. when doing accesses within a given page .. is given as ~28.5 MHz (not 16.66 MHz).

Over time, memory chips have been redesigned to reduce performance bottlenecks. Some currently common types of memory (with ~burst access speeds) are:

  • Fast Page Mode DRAM: 60 ns, 28.5 MHz page access
  • Extended Data Output DRAM: 60 ns, 40 MHz page access
  • Synchronous DRAM: 100 MHz, 66+ MHz burst DRAM access (has 2 32-bit address lines for on-chip interleaving ... the DIMM packaging)
  • Burst EDO DRAM: 66 MHz, 66 MHz burst page access


MODEMS

56K modems have been a mess. In February of 1998, the "International Telecommunications Union" (ITU) will settle on a single 56K technical standard. In September of 1998, the ITU will finalize the wording for the 56K standard. After February of 1998, people with 56K modems will need to upgrade to the new standard.

"X2" technology from US Robotics .. with Motorola, AOL, CompuServe, Prodigy, MCI, DELL, and many ISP sites. See http://www7.shoppingplanet.com (PC Newsletter of 1/20/97) See "http://x2.usr.com".

"K56plus" from Rockwell. "F.flex2" from Lucent (AT&T). "K56flex" from Rockwell and Lucent .. with 3COM, AST, Compaq, HP, Toshiba, and many computer/modem manufacturers.

http://math.arizona.edu/~swig/documentation/home_computing/cpu/index.php
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